December 2020 Medium/Long Term Pattern Discussion.

[TellicoWx]

Just now, Carvers Gap said:

Saw the same thing and laughed.  Bout the only positive from that which I see, is that it must be cold for it to snow that far south....plenty of time for that to trend NW, right?

Yeah..made me laugh too...00z NAM made things interesting.

[TellicoWx]

00z 3k NAM 

[Carvers Gap]

5 minutes ago, TellicoWx said:

Yeah..made me laugh too...00z NAM made things interesting.

Yeah, I normally like seeing storms underneath.  Always think the NW shield delivers, even if marginally.  I was wondering why that wasn't showing up.  Looks like the slp is a bit deeper.

[TellicoWx]

00z HRRR

[John1122]

24 minutes ago, PowellVolz said:

Talking Wednesday here?


.

Sunday night into Monday. 

[John1122]

As we get closer in the snow shield has expanded across Arkansas and now across West Tennessee on the hi-res models.  Hopefully it expands state wide. If so it will look like the good Euro run from about 5 days ago. 

[TellicoWx]

6 minutes ago, Carvers Gap said:

Yeah, I normally like seeing storms underneath.  Always think the NW shield delivers, even if marginally.  I was wondering why that wasn't showing up.  Looks like the slp is a bit deeper.

00z HRRR/3k NAM is kinda what I had playing out in my mind the other day. Global models usually tend to struggle when BL issues ars as close as it has been...meso models seem to be adjusting as we get closer..if rates are close to what's modeled, could def see a nice event west of the plateau...rooting for those guys.

[AMZ8990]

29 minutes ago, John1122 said:

As we get closer in the snow shield has expanded across Arkansas and now across West Tennessee on the hi-res models.  Hopefully it expands state wide. If so it will look like the good Euro run from about 5 days ago. 

Might be a nice surprise!  Fingers crossed 

[John1122]

1 hour ago, AMZ8990 said:

Might be a nice surprise!  Fingers crossed 

Pulling for you and Kevin, as well as our mid valley guys. 

[John1122]

The Euro isn't as aggressive as the short range hi res models for western areas but it was better than 12z for middle Valley and Plateau/SEKy areas. 

[John1122]

It may be wrong but the Euro has been locked in here for a good number of runs in a row. 

 

[weathertree4u]

Not sure how reliable the CFS model is but it builds a glacier in the lower 48 for the first two weeks of January. 

[Holston_River_Rambler]

4 hours ago, John1122 said:

It may be wrong but the Euro has been locked in here for a good number of runs in a row. 

Now the NAM, RGEM, and the RAP (show here for full snow weenie effect) have come around to some version of what it has been showing. 

 

 

 

Scratch that the 06z new HRRR looks pretty  for y'all out in parts of Middle and west TN

 

It drops the High Knob Hammer with 8 inches at LPN. All other models cut that in half. RGEM even gets into the coveted purple area in its snow precip. depiction just west of Nashville, for small window. 

Rooting for y'all in Nashville and SWVA and hoping i can get a surprise change over too. 

 

 

[Holston_River_Rambler]

Stole the idea to look for this off Jeff Piotrowski on twitter, but this a stout disturbance and lapse rates (maybe??) are helping create some convective snow in western OK. I think the disturbance if forecast to become less wound up as it moves across our area, but I wonder if any one can get some thunder 24 hours from now?

 

[AMZ8990]

3 hours ago, Holston_River_Rambler said:

Now the NAM, RGEM, and the RAP (show here for full snow weenie effect) have come around to some version of what it has been showing. 

 

 

 

Scratch that the 06z new HRRR looks pretty  for y'all out in parts of Middle and west TN

 

It drops the High Knob Hammer with 8 inches at LPN. All other models cut that in half. RGEM even gets into the coveted purple area in its snow precip. depiction just west of Nashville, for small window. 

Rooting for y'all in Nashville and SWVA and hoping i can get a surprise change over too. 

 

 

If only Kentucky and Tennessee were in the opposite spots, we would have big time  storms every year.  Kentucky gets a lot of big snows, more than people realize I think!

[AMZ8990]

Temps right now are about 7 degrees below where they were estimated to be at this time, hopefully that continues throughout the day.  Northeasterly for the wind.  Oklahoma City reporting snow as well as the Tulsa area.  Those guys could cash in big since their so close to the rain/snow line.  I’m hoping that works out for some of our forum as well.  Either way though it’s something fun to keep up with today and tomorrow.  Hope everyone is doing well.

 

AMZ

[tnweathernut]

1 hour ago, AMZ8990 said:

Temps right now are about 7 degrees below where they were estimated to be at this time, hopefully that continues throughout the day.  Northeasterly for the wind.  Oklahoma City reporting snow as well as the Tulsa area.  Those guys could cash in big since their so close to the rain/snow line.  I’m hoping that works out for some of our forum as well.  Either way though it’s something fun to keep up with today and tomorrow.  Hope everyone is doing well.

 

AMZ

Good luck over that way...  hope some from west to middle TN find a surprise or two with this one.

[Carvers Gap]

Euro 12z WxBell snow algorithm definitely showing snow showers for much of west and middle TN for storm one.  Storm two - rainer...though extreme NE TN/SW VA is not written in stone for this one yet I don't think.  If DC is getting a good track, sometimes TRI can get in on that.  Anyway, storm one has anywhere between. .5 - 2" from a line from Memphis to the northern Plateau. 

 

[Carvers Gap]

I do think WxBell is a bit generous with its snow algorithms on the 3hr and 6hr maps.  Here you go for middle and west areas of the subform...Also, nice look for areas of SE KY and SW VA.

[Daniel Boone]

1 hour ago, Carvers Gap said:

I do think WxBell is a bit generous with its snow algorithms on the 3hr and 6hr maps.  Here you go for middle and west areas of the subform...Also, nice look for areas of SE KY and SW VA.

Let's hope the Euro still has a bit of a warm bias and more of the area gets in on some accs.

[nrgjeff]

Tonight and midweek systems still have some promise at higher elevations like the Plateau and Mountains. Perhaps even an upward surprise there. Lower elevations look too warm despite 850 Ts. Thickness and surface forecasts are not there.

Looking to the New Year models (ensembles and weeklies) all seem to be trending colder at the very end of December. We'll see if it holds. Failure modes include Alaska or Greenland. About a third of the member have both blocked, which is of course bullish.

 

[Daniel Boone]

4 minutes ago, nrgjeff said:

Tonight and midweek systems still have some promise at higher elevations like the Plateau and Mountains. Perhaps even an upward surprise there. Lower elevations look too warm despite 850 Ts. Thickness and surface forecasts are not there.

Looking to the New Year models (ensembles and weeklies) all seem to be trending colder at the very end of December. We'll see if it holds. Failure modes include Alaska or Greenland. About a third of the member have both blocked, which is of course bullish.

 

Yeah, unless skies stay clear for a good while 2night, lower elevations are pretty much for sure out of luck. However, by the looks of it, timing regarding that is not good as clouds are rolling in in time to hold the days heating in.

[PowellVolz]

My location will sit this one out, so I'll gladly root for y'all elsewhere in the forum area.

Save me a chair. I’m joining you.


.

[AMZ8990]

Temps are holding at 46, 5 degrees below the forecasted high of 51.  No rain yet but it’s overcast, been that way most of the day as well.  System looks great for those west of us, they seem to be cashing in 

[Holston_River_Rambler]

Latest HRRR hammers Clay and Knox counties, KY. 13.3 jackpot spot. I have absolutely no confidence in that sort of an amount, but that model starts to change that area over as early as 1 - 2 AM

 

NAMs backed off sig. from their 6z runs throughout today, but the RAP seems to be coming back a bit. 

[AMZ8990]

 

Big implications if this comes to pass 

[Carvers Gap]

The 18z RGEM(beginning at hour 60) implies that there may be some slick spots during storm #2 in valley locations.  Not sure I buy it, but is definitely on the model.  Cold is quickly scoured out, but it does imply that there may be initial ice or mix north of 40 and along the I-81 corridor.  I am absolutely not calling for that, but just wanted to give it a mention.  Don't see a lot of evidence on other modeling, but the RGEM has been decent in recent years.

[nrgjeff]

Sorry Judah those are bird farts. Continue jostled but tight strato PV. We'll have to hope for -AO in the troposphere. Sorry I'm in Cynic Mode.

There is still hope for after Christmas into early January. While NWP keeps losing sharp cold waves, it's also losing blowtorch days. Variable can get the job done in January.

[Holston_River_Rambler]

What do y'all think of the NAM's depiction of ice in Sequatchie county? :

Looks like it wants to bank some low level cold air up against both sides of the Sequatchie Valley. 

 

I'm not really interested in chasing ice, for ice's sake, seems waaay too dangerous. But from a TN Valley microclimate standpoint, I'm curious. The Icemeisters over in the Carolinas seem to put a lot of stock in the NAM's thermal profiles, but I'm not sure if the same thing would work out over here?

[Carvers Gap]

27 minutes ago, Holston_River_Rambler said:

What do y'all think of the NAM's depiction of ice in Sequatchie county? :

Looks like it wants to bank some low level cold air up against both sides of the Sequatchie Valley. 

 

I'm not really interested in chasing ice, for ice's sake, seems waaay too dangerous. But from a TN Valley microclimate standpoint, I'm curious. The Icemeisters over in the Carolinas seem to put a lot of stock in the NAM's thermal profiles, but I'm not sure if the same thing would work out over here?

Potential recipe for trouble where cold air banks up against the western side of the Valley against the Plateau.  Both the 12z RGEM and 3K NAM show this to some extent, which to me is amazing that modeling can do that.  When a low sits to our SE and we have marginal air masses that dip below freezing overnight, sometimes precip can lock the cold against the valley floor.  Then the winds out of the east push that cold into pools against the mountains.  Doesn't happen often, but it does happen.  Very difficult to forecast.  MRX does have a mention for extreme NE TN and SW VA.  My point and click this AM, had me with a mix for much of the morning on Weds.  Just have to wait and see.  Tricky forecast.  I don't expect any significant ice accumulation, but ANY ice accumulation on roadways is a royal pain in the butt.